It fits very tight just like it is supposed to for rolling without a gi. I'm 6'2 and roll light heavyweight and it fits me like a glove. Imagine a very heavy weight compression shirt. Not at all binding or restrictive even around the biceps or under the arms.

Sizing isn't given for rash guards due to the elasticity of the product. Because of this factor, sizing done on a rash guard is extremely inaccurate. It is recommended to order the same size rash guard as a t-shirt you would purchase.